The Clinical Center has requested that the BEIP install two additional Patient Electronic Monitoring Systems (PEMS) on the 5E and 3E Nursing Units. A system that alerts the nursing staff when a patient (or patients) is leaving the nursing unit is a welcome aid in the care of patients with Alzheimer's disease or other dementias. The system is based on a wristwatch-size radio transmitter worn by the patient. A detector unit, placed at the two exit doors, senses the presence of any patient wearing a transmitter watch. With the detection of a patient's transmitter, a microprocessor based controller locks the exit door, activates an alarm, and sends the patient's name and location to a personal computer, which displays and records the time and date of each attempt a patient makes to leave the unit.